Activity 6: Water Quality

Unit 2 Home

Overview:

In this activity you will examine some of the common types of water pollutants and their effect on water quality. You will learn about water quality guidelines, such as the Water Quality Index, and different types of water tests. You will analyze data on the Water Quality Index levels of the Great Lakes and participate in a discussion about the water quality of the Great Lakes. You will complete a study of the effects of a chemical spill on the water quality of a creek. Finally, you will research a variety of threats to your home drinking water supply.

Content:

All living things require water. Whether you live in a large city, a small town, or in the country, what you do at home, work, or school may affect the quality of your local water supply. Water is used in every Canadian home, for transportation, manufacturing, agriculture, and industrial processes. These uses can put major stress on the quality of our water.

Water Pollution Note

U2A6 - Water Pollution

Impacts on water quality

1. Excessive Nutrients

Wastewater from sewage treatment plants, runoff from agricultural lands, and water discharge from industries, such as pulp and paper mills, add large amounts of excess nutrients, including nitrogen and phosphorus, to our water systems. These excess nutrients may result in excessive plant growth, and algae blooms, that degrade water quality and reduce the amount of available oxygen for fish and other aquatic organisms.

2. Chemicals

A range of household and industrial chemicals affect our water quality. Municipal wastewater releases household chemicals, pharmaceuticals and chlorine into our water supply, decreasing water quality for human use and aquatic ecosystems.

Industry and manufacturing release various toxic chemicals, heavy metals and other substances into our water systems, as part of their industrial waste. These chemicals pose potential health risks for humans and wildlife.

Events, such as large chemical spills and oil spills from tanker ships, also pose a threat to water quality and aquatic ecosystems.

3. Acid Precipitation

Acid precipitation can lead to acidifying lakes. As a result, many aquatic organisms die and lakes can no longer support fish and other organisms in water bodies that are too acidic.

4. Sediment

Poor agricultural practices and construction produce dust and may result in soil erosion that adds sediment and silt to our water systems. This increased silt diminishes the quality of our drinking water and may pose a threat to certain organisms in aquatic ecosystems.

5. Biological Contamination

Degradation of our drinking and recreational water supplies from microbiological contaminants, such as bacteria, protozoa and viruses, is a major concern. Runoff from land fertilized with manure, biosolids, livestock walking in streams, and municipal wastewater, are major risks of biological contamination to water sources, making them unsuitable for many human uses.

CHECK YOUR UNDERSTANDING

Excessive weed growth, due to excess nutrients in the water, causes what problems for fish and other aquatic organisms?
Chemical pollutants not only pose a health threat to humans and wildlife, but also affect what other human activities?
What types of activities pose major risks of microbiological contamination in our water bodies?

Water Testing and Monitoring

Water testing and monitoring are two important tools, used to maintain good water quality and protect aquatic ecosystems. A wide variety of tests are routinely used to monitor water quality.

1. Bacteriological Testing

Bacteriological tests determine the presence of disease-causing bacteria. The most common test is a coliform test. Coliform bacteria live in the intestines of animals; their presence indicates the water has been contaminated with feces and may contain disease-causing bacteria.

2. Ion Testing

Ion tests measure the amount of various mineral impurities in the water, such as heavy metals, phosphorus, nitrates, and sulphates. Ion tests can also determine the acidity, or pH, and the hardness of the water.

3. Chemical Testing

Testing for specific human-made chemicals is not routinely done, due to the expense. If a water sample is suspected to be contaminated by specific chemicals, then tests for that chemical can be done.

4. Biological Testing

A powerful, although indirect, method for testing water quality is to look at the species of organisms in the water. Certain species are particularly sensitive to reduced oxygen, turbidity or toxic chemicals. The presence and abundance of certain organisms yields information about the overall water quality. This method often utilizes an undisturbed, but similar, site for comparison purposes.

5. Collecting Samples

When collecting water samples for water quality testing, the most common method is depth-integrated sampling. This is when water from various depths are collected together as one sample. Alternatively, depth-specific sampling can be used to collect water from one specific depth to test only the water from that depth.

The diagram below shows water being collected at many depths in depth-integrated sampling, and at one specific depth in depth specific sampling.

Long-term water quality monitoring helps identify trends in water quality for a particular body of water. Is the water quality improving or is it decreasing and should action be taken to protect the water quality and aquatic ecosystems?

Water Quality Guidelines

Water quality guidelines are numerical values for the physical, chemical, and biological characteristics of water that when exceeded, have a potential to cause harm.

There are specific guidelines depending on how the water is being used: for drinking, recreation, agriculture or to support aquatic life.

1. Canadian Water Quality Index (WQI)

The WQI is used to assess the suitability of water bodies to support aquatic life. Water testing data for various characteristics, such as acidity, lead concentration, and dissolved oxygen, are converted into a single overall water quality rating between 1 and 100. The index numbers are divided into five categories; the higher the number, the better the quality of water to support aquatic life.

2. Guidelines for Canadian Drinking Water Quality

These guidelines set minimum standards for safe drinking water in Canada. The guidelines are primarily based on the potential health effects of substances in the water; and aesthetic characteristics, such as taste and smell. The potential for identifying microbiological contamination of drinking water is given the highest priority.

3. Guidelines for Canadian Recreational Water Quality

Published by Health Canada, these guidelines mainly deal with reducing the risk of infection from disease-causing microorganisms, illness or injury due to chemical or physical properties of water used for recreational activities, such as swimming.

CHECK YOUR UNDERSTANDING

Which of the three water quality guidelines (Water Quality Index, Canadian Drinking Water Quality, or Canadian Recreational Water Quality) would be used in each of the situations below?

In the summer, some beaches in the Toronto area have posted 'no swimming' signs due to high levels of bacteria.
Acid rain has polluted numerous lakes in Northern Ontario making them unsuitable for fish.
Towns that get their water from wells must regularly test their water supply.

Class Assignment: Safe Drinking Water Poster

Depending on where you live, your drinking water may come from a lake, or river, groundwater, or an individual well.

1. Research the source of your home drinking water

2. and the major threats to the quality of water from that type of source.

Based on your research, create a poster that explains what your home source is, and two threats to the quality of the water supply. You will make your poster using Canva

. You will need to sign in to Canva with your ugcloud gmail account.

The rubric is posted in google classroom

When you have completed your poster you will submit it in google classroom for Ms. Coleman to mark.

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